The present application relates to carbon nanotubes (CNT), a method of preparing the same and an element using the same. Specifically, the present application relates to a method for preparing carbon nanotubes by an arc-discharge method. The carbon nanotubes obtained by the method have higher purity and narrower diameter distribution as compared to conventional methods.
As one-dimension carbon nanomaterials, carbon nanotubes (CNT) have attracted considerable attention for their superior electrical, mechanical and chemical properties. Further study on nanomaterials brings great potential application of carbon nanotubes in a wide range of fields such as electron source for field emission, carbon nanotube field effect transistor, hydrogen storage materials and high-strength fiber, and the like.
Carbon nanotubes can be classified as single-walled carbon nanotubes and multi-walled carbon nanotubes according to the number of the layers of the carbon atoms to form the wall. Multi-walled carbon nanotubes are multi-layered by encasing several single-walled carbon nanotubes with different diameters. In practical research and application, single-walled carbon nanotubes and multi-walled carbon nanotubes with fewer layers are important due to their unique electrical, thermal, mechanical and chemical properties.
Conventional methods for preparing carbon nanotubes include an arc-discharge method, chemical vapor deposition (CVD) and laser evaporation, and the like. So far as we know, the arc-discharge method is one of the most efficient techniques for large-scale production of high quality carbon nanotubes. Many efforts have been made by optimizing parameters such as the kind of catalysts (or promoter) and inert gas, pressure, current or voltage, temperature, or the like for improving the purity and yield of as-prepared carbon nanotubes and controlling the diameter distribution. For example, B. P. Tarasov, et al. synthesized carbon nanostructures with very high purity by using Y—Ni alloy as catalysts (B. P. Tarasov, et al, Synthesis of carbon nanostructure by arc evaporation of graphite rods with Co—Ni and YNi catalysts, Carbon 41, 2003, 1357-1364). H. Li et al. achieved higher purity of single-walled carbon nanotubes (SWNT) by adding FeS into the Y—Ni alloy catalysts as a promoter (H. Li, et al, Direct Synthesis of High Purity Single-Walled Carbon Nanotube Fibers by Arc Discharge, J. Phys. Chem. B 108, 2004, 4573-4575).
Currently, there is still a need for a method for preparing carbon nanotubes with high purity and narrow diameter distribution.